This invention relates to a tape cassette and, more particularly to a tape cassette having tape guides not formed in one piece with the housing of the cassette such as the VHS video cassette.
Conventional tape cassettes, such as for VHS video tapes, comprise an upper casing and a lower casing molded separately and joined together to form a cassette housing, a pair of tape reels contained in the housing, with a length of tape wound around one of the reels so as to be supplied to and taken up by the other reel. To guide the tape, there are usually provided a pair of tape guides, right and left, inside the housing.
For the purpose of proper guiding, the tape guides must be fixed rather than being turnable so that the vertical straightness of the guides can be secured and the wear of the posts supporting the guides be avoided.
To keep the tape guides unmovable, various proposals have been made. Japanese Utility Model Application Publn Kokai No. 54-70513 achieves the end by fitting a cylindrical metallic tape guide to each of tape guide posts molded in one piece with the cassette housing and having three or more axially extending projections formed on the post body.
Utility Model Application Publn Kokai No. 55-132783 discloses bosses on which cylindrical metallic tape guides are press-fitted. Each boss is formed with portions larger or smaller in diameter than the inside diameter or outside diameter of each tape guide in such manner that the guide fits immovably to the boss.
Patent Application Publn Kokai No. 3-187081 provides bosses on which cylindrical resin tape guides are fitted. The part of each boss that does not contact the tape is tapered and a rib is formed in the lower portion of the taper. A tape guide is then press-fitted to the boss.
It has been in practice to provide tape guide posts with ribs and then press-fit cylindrical tape guides, one for each, to the posts to keep them from turning. When the tape guides are made of metal, there is no possibility of the tape guides being deformed upon press fitting. However, they can wear off or deform ribs of plastic casings, or the need of polishing can add to the manufacture cost. In recent years tape guides made of resins have come into use. Resin tape guides have the danger of being deformed upon press fitting to their guide posts. Attempts to avoid this have been made as proposed by Patent Application Publn Kokai No. 3-187081 in which ribs are provided in locations where they are kept out of contact with the tape.
However, when resin tape guides are used, the height of the tape guide posts and that of the ribs along which the tape guides are to be press-fitted can sometimes deteriorate the (vertical) straightness of the tape guides, resulting in irregular sliding contact with the tape, unstable running of the tape, or partial elongation of the tape that makes recording or reproduction impossible.